Button bottom pile



May 29, 1951 H. F. CAUDILL BUTTON BOTTOM PILE Filed Aug, 9, 1948 I N VENTOR.

Patented May 29, 1951 BUTTON BOTTOM PILE Howard F. Caudill, ArlingtonHeights, Ill., as-

signor to Western Foundation Corporation, Chicago, Ill., a corporationof Delaware Application August 9, 1948, Serial No. 43,201

(Cl. (i1-57) 5 Claims.

The present invention relates to a cast-in-place concrete pile employinga steel shell resting upon an enlarged preformed point. This type issometimes designated as a button bottom pile.

The present invention is an improvement upon the invention disclosed inthe patent to J. H. Thornley, No. 1,778,925, of October 2l, 1930.

According to said Thornley patent, No. 1,778,925, a short section of theinner shell is ernbedded in the body of the point, and the main sectionof the shell is spliced to the short section by an intermediate sectionor wrapping held to the adjacent sections by encircling clamping hoops.Such construction involves the following disadvantages which the presentinvention cures:

(1) The joint is inconvenient to make and is not always tight.

(2) Since the splice can only be made before the point is driven, thepoint is driven with the shell attached. This involves someinconvenience in handling, and the jarring of driving the point tends toloosen the joint in the shell.

The object of the invention is to provide a pile and a method ofconstructing the same which will uniformly give the desired support,with the certainty that is to be sought in foundations, and with economyin time, labor and material.

The theory of the present pile is relatively sirnple. It consists'inproviding a pre-cast driving head or point, which is made of a diameterlarger than the driving sleeve, hence the name button bottom. In effect,the sleeve with the enlarged head is a probe, this probe being thrustdown into the soil to find a suitable resistance which will provide therequired bearing. Then the temporary shaft of the probe is replaced by apermanent structure of suitable material to provide a permanent shaft orcolumn resting upon the probe head and constituting the nished support.

According to the present invention, a driving header point is preformedof concrete. Itis o provided with a lower driving face which may beapplying impact pressure to the head. The head is of a diameter which issubstantially larger than that of the driving sleeve. The head pushesthe soil away as it penetrates the soil to reduce temporarily thefriction with the driving sleeve as the point is driven downward in thenature of a probe. Since the diameter of the point or button is greaterthan the diameter of the driving sleeve, the friction on the latter willbe temporarily relieved, so that no false bearing value of the upperstrata will invalidate the driving formula. The point is driven to thepenetration required to carry the design load.

When the point or button has been driven to the desired distance orrefusal, the light inner shell is lowered into place down through thedriving sleeve. This light shell is joined to the driving point orbutton after the latter has been driven to seat. To join a shell inwater-tight relation to button or head after the same has been driven toseat far below the surface of the ground, is a problem presentingconsiderable difiiculty.

l The shell should be so joined to the point orbutton that it may becleared of water and sand, and it should be mechanically fastened -tothe button or point with sucient strength to resist heave of the soiloperating upon its sides whereby to prevent possible separation of theshell from the point or button. The shell is filled with concrete, andthe driving sleeve is withdrawn.

The present invention specifically provides a novel form of head orbutton, and a novel mechanism and method for fastening or joining thehead or button tothe shell. rl'he shell constitutes a novel part alsofor cooperation with the head and with the fastening means.

In order to acquaint those skilled in the art with the manner-ofconstructing and operating a device embodying myinvention, I shall nowdescribe, in connection with the accompanying drawings, a preferredstructure and mode of constructing the same. v

In the drawings:

Figure lis a vertical section showing the driving sleeve in theoperation of driving the point 01 button to seat; v

Figure 2 is a similar section showing the point or button driven toseat, the permanent shell lowered into place, and the operation of theattaching means;

Figure 3 is a section on an enlarged scale, with respect to Figure 2,showing the permanent shell and the button and the attaching means forjoining the two permanently; f

Figure 4 is a front elevation, partly in section, of the finished pile;

Figure 5 is a fragmentary view illustrating the application of a sealingcompound between the top of the button and the bottom of the permanentshell; and

Figure 6 is a bottom plan view of the permanent shell, showing the holein the base plate.

The button, or point I, comprises a main body portion 3 which has adriving face In the preferred form, the driving face is conical with theapex downwardly, but this particular form is optional, since the drivingface may even be flat. In the form shown in the drawings, the maximumdiameter is at the junction 5 of the driving face 4 and the main bodyportion 3, which latter preferably is tapered inwardly and upwardly. Inother words, there is no necessity for any extended length ofmaximumdiameter.

The upper end of the button I has a generally horizontal convex clampingface 6 from the center of which extends the stud 1. The area of the face6 radially outside the stud I is the loadbearing area upon which theshaft of the pile rests when the pile is completed. Preferably a shortneck 8 extends upwardly above the annular conical driving shoulder 9,this neck 8 serving to assist in aligning the driving point or buttonwith the driving sleeve 2. The neck or shank 8 is in the case of thenominal 12 inchv pile of a diameter approximately 121/2 inches. Thecrown of the face 6 is approximately one inch, and the stud 1 is in thisinstance preferably 'V8 inch diameter, approximately 9 inches long, andis provided with a heavy thread of about seven threads to the inch. Themaximum diameter of the button or head I is in this instance about 171/2inches. The driving sleeve 2 has an inside diameter in this instance ofapproximately 13 inches. It is provided at its lower end with areenforcing ring I0 which is welded to the sleeve. The tapered shoulder9 cooperates with a correspondingly tapered surface on the inside of thereenforcing ring ID to center the sleeve 2 with respect to the button Iand to permit the application ofV impact pressure through the sleeve andreenforcing ring IB. lThe tapered ring Il) bearing on the taperedshoulder of the point or button acts in compression upon the concretebody whereby the impact pressure has less tendency to crack or break theconcrete body I. The angle of this taper may be varied, but ispreferably of the order of 60 from the horizontal. It should not be solow as to cause sticking.

When the driving sleeve is applied to the button, the two parts may besealed together by a roofing mastic or similar sealing compound, so thatground water will not enter the shell 2 until the parts are purposelyseparated.

After the point has been driven to the desired bearing value, asindicated in Figure 2, the light sheet metal shell I2 complete and inone length is lowered inside the sleeve 2. IThe shell I2 is intended, asshown in Figure 4, to be filled with concrete to complete the pile, butat the stage shown in Figure 2, it is necessary to join. the shell tothe button I by a means which can be operated from the top of the hole,and which will nevertheless provide sufiicient strength againstseparation that the friction of the ground heaving up around the sidesof the sleeve I2 as may later be the case when other piles are driven inthe neighborhood, will not cause dislocation of the shell I2 withrespect to the button I. The shell I2 ispreferably made of light sheetmetal stock, which, for instance, may be`18 gauge, with an outsidediameter of 121/4 inches and corrugations 1A; inch, deep each way. Thisshell is preferably made up of spiral strip joined by a lock seam, andof the length desiredl to carry the same from the desired point abovethe ground down to the button I as a continuous piece. A dished bottomplate or closure I3 shown in bottom plan in Figure 6 is attached bywelding to the lower end of the shell I2 to form a strong, tight jointwith the said shell. A hole of approximately two inches diameter isformed in the center of the bottom plate I3 to pass overthe threadedstud 1. The hole i4 is at the center of the upwardly crowned bottomplate I3, the crown acting as a guide tending to assist the operator inpassing the shell I2 and its base plate I3 down over the stud 1, asshown in Figure 2. When the shell has thus been dropped down over thestud, it is then in order to thread the clamping nut I5 over thethreaded stud 1 to clamp the bottom plate against the clamping face 6 ofthe button or point. The crown in the bottom plate I3 corresponds to thecrown on the clamping face 6, so that the two parts may fit fairlyclosely. Additionally, a layer of roofing mastic, as indicated at I6 inFigure 5, may be applied to the two cooperating surfaces, or to eitherof them to form a tight seal for excluding ground water and sand..

To apply the clamping nut I5 is simplified by provision of thefunnellike flange II formed on the lower part of the nut I5. The nut I5has apolygonal top portion, preferably square with one face providedwith a depression at I8, as shown in Figure 3, to. be engaged by a snapsocket wrench I9, as shown in Figure 2. This wrench I9 comprises arelatively long stem 20 with a barrellike guide 22 at the lower endadjacent the socket portion 23. The socket 23 has a spring plunger ofwell known type 26 for entering the depression I'I in the nut I5, andthereby holding the nutin the socket wrench. By lowering the tool andthenut down through the shell I2 until it rests on the stud and rotatingthe same, the upwardly and inwardly tapered. bottom surface of theflange II will guide itself upon the stud 1, and may thereupon be drawnup tight. After the nut has been turned home, the socket wrench may bedetached by an upward pull and the tool removed. Thereupon, the shell I2may be filled with concrete of the desired composition and strength, thedriving sleeve 2 withdrawn, and the job is complete. The upper end ofthe pile may be connected to a structure to be supported in any wellknown manner. A pile cap is one common method.

The advantages of this construction and method of operation areapparent, since the button or point is of substantially larger diameterthan the sleeve so as to clear the driving sleeve of lateral friction toa great extent. The positive bearing value is discovered by theresistance which the button encounters. Since the resistance to drivingis the test of the bearing value of the pile, no false bearing value ofthe uppei` strata on the side walls of theY pile will beV involved.

The method of driving and installing the shell is such that the shellcannot be torn or distorted in the process of locating it. The permanentshell can be inspected before it is concreted, and it is left in placeas a form for the concrete.

I claim:

1. A driving point for a button bottom pile comprising a circularprecast body of concrete having a head portion adapted to be exposed tothe soil during driving and having a top clamping face, a threadedrodlike clamping stud of small diameter as compared to the diameter ofthe clamping face anchored in the body and projecting axially upward outof said face, said face being circular and of a diameter substantiallyless than that of the head portion, the area of the 5 said top clampingface radially outside the clamping stud constituting the mainload-bearing area for supporting a pile shaft above it and an annularconical driving shoulder below said clamping face for receiving impactpressure to drive said point to a supporting stratum.

2. In a button bottom pile, the combination of a precast concrete bodyconstituting a driving point having a top clamping face, a stud anchoredin said body and extending from substantially the central part of theclamping face, a tubular light steel shell having a bottom plate closingthe lower end, said plate having a central opening adapted to be slippedover said stud and a clamping nut threaded over the stud to clamp thebottom plate to the said clamping face.

3. In a button bottom pile, the combination of a precast concrete bodyconstituting a driving point having a convex top clamping face, athreaded stud anchored in said body and extending from substantially thecentral part of said clamping face, a tubular light steel shell, aclosure plate for the lower end of the shell, said plate having acentral hole and being concave on the bottom toward the hole whereby toguide the same over the stud, and a flanged clamping nut threaded uponsaid stud to clamp the shell to the point, the flange of the nut beingof larger diameter than the hole whereby to close the same.

4. As an article of manufacture a button bottom pile shell comprising athin walled corrugated steel shell open at its upper end and having adished up closure plate welded to the lower end thereof, said closureplate having a central bolting aperture.

5. Method of installing a button bottom pile, which comprises forming aprecast driving point with an enlarged body, a clamping stud and anannular driving shoulder at the upper end thereof driving said point byimpact pressure upon the shoulder applied through a driving sleeve ofless diameter than the point until the point is driven to loadsustaining seat, then lowering a light sleeve shell through the drivingsleeve onto the point and thereafter clamping the sleeve t0 the point,lling the shell with concrete and withdrawing the driving sleeve.

HOWARD F'. CAUDILL.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 739,268 Shuman Sept. 15, 19031,645,398 Pierce Oct. l1, 1927 1,778,925 Thornley Oct. 2l. 1930

